ANZ's Truckometer is predicting solid economic growth for the rest of the year and a positive start to next year.
The Truckometer, which uses traffic volumes to measure Gross Domestic Product, fell slightly in August after a sharp rise in July.
The heavy traffic index, which is an indicator for the economy now, fell 1.5%, while the light traffic index, which predicts GDP six months ahead, fell 0.3%.
ANZ senior economist Sharon Zollner said the light traffic index suggests the current lift in economic momentum will persist.
"The light traffic index - because that's been going up - that should suggest that the heavy traffic index, and of course GDP, should show some pretty solid growth over the next six months."
But she said there are downside risks to the second quarter GDP number that will be released later this month.
"That's because of the drought impacts which will be only partly captured by the traffic flow data and by our other indicators as well."
